改良红层工程性能与环境耐久性研究进展

红层在我国东南、西南、西北地区广泛分布,因其膨胀收缩性、遇水崩解性、岩体软弱性等特点,往往不能直接作为填料应用于路基工程,必须进行物理或化学改良处理。通过文献调研,本文从红层崩解机理、工程改良方法、改良效果及环境耐久性等方面对国内外研究进行了梳理。并结合现有研究,提出未来应加强环境荷载(如干湿、冻融作用)及静、动荷载单独或耦合作用下改良红层的耐久性研究。

汽车零部件环境耐久试验参数优化方法研究

该文对汽车零部件环境耐久试验参数优化方法进行探讨,阐述可靠度、试验参数的概念和计算方法,基于规定的可靠度、置信度对环境耐久试验参数进行调整,包括试验时间、样品数量、温度、湿度等,以满足项目验证要求,同时分析试验成本优化方法,通过环境耐久试验参数及试验费用的计算得出试验成本的最优解,并通过具体案例进行说明。

结构胶接接头湿热环境耐久性研究概述

相比于传统机械连接,如铆接、焊接和螺栓连接,结构胶接技术有着诸多优势,近年来在很多工业领域得到了广泛应用。由于胶黏剂本身具有高分子聚合物材料的特性,使得胶接接头的环境耐久性成为关乎工程结构连接可行性和长期服役可靠性的关键问题。在概述结构胶接接头湿热环境耐久性研究工作的基础上,分别从影响胶接结构性能的环境湿度、温度及其耦合作用等角度展开讨论,介绍了国内外研究人员取得的研究进展和成果。指出了今后的研究方向:结合多种观测尺度下的环境老化试验和数值仿真方法,探究胶层吸湿、蠕变、热膨胀和吸湿膨胀等环境老化行为,利用模型预测方法模拟其在多场耦合工况下的多种力学性能退化行为,从而为胶接结构的工程设计和应用提供更加可靠的理论建模和试验数据支持。

OLED显示模块的使用和储存环境耐久性的监测方法

介绍了OLED显示模块的技术特点,总结和分析了OLED显示模块的标准试验环境和环境耐久性试验的要求,为生产企业或检测机构进行OLED显示模块在使用和储存过程的耐久性试验提供依据。

新能源整车控制器环境耐久测试系统设计

为解决新能源汽车整车控制器(VCU)的环境耐久测试问题,设计了该测试系统。系统采用NI PXI系统实现输入信号模拟和输出信号在线检测,负载箱模拟整车执行器负载,环境箱模拟控制器工作环境,基于LabVIEW开发的上位机软件全程监测控制器的运行状态,对信号测试结果进行实时显示和数据存储。结果表明,该系统性能稳定,可快速、自动完成对整车控制器的测试,满足测试要求,提高了整车控制器的测试效率。

泡沫轻质土的环境耐久性试验研究

近年来,随着科技的发展和社会的进步,泡沫轻质土广泛应用于工程道路施工项目中,以其独有的轻质性、高流动性和灵活调整性等优势大大提高了施工材料的稳定性。在进行泡沫轻质土使用前需要进行前期的环境耐久性试验,检验泡沫轻质土的耐环境性,从而为保证工程施工和建设质量提供材料支撑和技术保障。本文对泡沫轻质土的环境耐久性试验进行详细分析和论证,对可能影响稳定性的指标进行研究,实验证明泡沫轻质土具有较强的环境耐久性。

用于改善飞机螺旋桨防结冰性能的硅橡胶超疏水表面耐久性和延迟结冰性能研究

飞机螺旋桨在服役过程中由于地域性差异和天气的变化可能会遇到各种苛刻的环境。因此,理想的飞机螺旋桨用橡胶复合材料必须具备极好的超疏水性能、延迟结冰性能和环境耐久性。本文通过模板法和高温处理制备了硅橡胶超疏水表面,研究了低温冷冻、高温加热和紫外辐照对超疏水硅橡胶疏水性能的影响。此外,为了揭示超疏水硅橡胶在空气湿度影响下的延迟冻结行为,设计了延迟结冰装置,并利用扫描电子显微镜(Scanning electron microscopy,SEM)和能谱仪(Enery dispersive spectrometer,EDS)分析了超疏水性能的变化和延迟冻结机理。结果表明,制备的超疏水硅橡胶具有良好的环境耐久性和延迟冻结性能,在飞机螺旋桨超疏水电热防冰方面具有实际应用价值。

影响混凝土结构耐久性的环境因素及改善措施

阐述了影响混凝土结构耐久性的环境因素,结合新颁布的规范,总结了环境因素对混凝土结构耐久性影响的改善措施,以提高混凝土结构耐久性。

高温高蚀海洋环境下提高混凝土结构耐久性措施

吉布提是世界温度最高的非洲国家之一。新建的Assal湖盐业出口码头项目所在地更是位于吉布提最高温高腐蚀性的Ghoubet湾地区。本文通过对该项目实施过程中对提高混凝土结构耐久性的措施进行分析和经验总结,旨在为非洲、中东和其它高温高蚀海洋环境下,提高钢筋混凝土结构耐久性提供参考。

环境条件对连续碳纤维增强聚苯硫醚复合层板层间性能的影响

在制备高性能连续碳纤维(CF)增强聚苯硫醚(PPS)复合层板的基础上,考察了不同环境条件对连续CF增强PPS复合层板层间剪切强度(ILSS)的影响规律,包括温度、高低温循环及冻融循环。研究结果表明,在205℃时,连续CF增强PPS复合层板的ILSS保持率仍有40%左右;经历高低温循环或冻融循环后,ILSS随着循环次数的增加而下降,即使在经历较严苛的15次高低温循环(150℃,–50℃)或冻融循环循环(–50℃,100℃,)后,ILSS保持率仍达到76.5%以上。制备的连续CF增强PPS复合层板有较好的环境耐久性。

环保型浸渍漆及绝缘结构的环境适应性研究

对某环保型浸渍漆进行常规性能测试和冷冻-加热、高温浸水、冷热冲击、恒定湿热等环境耐受性试验,分周期测试了环境耐受性试验过程中浸渍漆的电气强度和粘接强度;基于该环保型浸渍漆制备了一种典型的绝缘结构,对该绝缘结构开展盐雾-湿热-振动和冷热冲击-浸水-振动等环境适应性试验,对比分析环境适应性试验前后绝缘结构的绝缘电阻、介质损耗因数及击穿电压。结果表明:该环保型浸渍漆具有良好的电气绝缘性能,基于该环保型浸渍漆的典型绝缘结构具备良好的环境适应性。

铁路路基工程试验检测技术应用研究

国家铁路网的关键环节,作为铁路建设的基石工程,负责锁定轨道工作,确保行车安全、顺畅运行以及高效运转。本文全面探讨了铁路路基的试验和监测技术,涵盖了土工试验技术、现场测定与评估技术、环境及耐久性检测、数据解析与仿真模拟等关键技术的具体应用。通过对土体的物理、化学及力学特性的深入分析和详细研究,为路基的设计、施工和维护提供精确的科学依据,进一步引导工程实践。

温度和湿度对碳纤维增强复合材料老化影响研究综述

碳纤维增强复合材料因其良好的力学、物理和化学性能,在多个工业领域获得了广泛应用。在工程应用中,关键结构的服役寿命和性能耐久性是一个不可忽视的问题。碳纤维增强复合材料通常以树脂为基体,而树脂易受环境影响发生老化,对复合材料的性能产生显著影响。本文首先介绍了环境温度对碳纤维增强复合材料性能的影响,并总结了水分扩散理论及常见的复合材料吸湿模型,然后整理了湿热耦合环境对碳纤维增强复合材料性能的影响效应,包括理论分析、试验方法以及有限元仿真等研究手段,最后讨论了碳纤维增强复合材料在湿热老化研究方面存在的问题和挑战,并对可行的研究方向进行了展望。

不含硼酸盐的环氧防火涂料制备及应用

研究了防火涂料的火焰传播指数、发烟指数、漆膜溶解失质量率、耐碳氢火焰能力及环境耐久性。研究表明:不含硼酸盐的环氧防火涂的漆膜溶解失质量率低于相应的含硼酸盐防火涂料,对环境水质干扰小;依据GA/T 714—2007测试其耐碳氢火焰防火性能,膜厚10 mm时,耐火时为160 min;依据GB 14907—2002和ANSI/UL 1709—2007测试其在各种环境下的耐久抗衰减能力<15%,证明了其能应用于高层建筑、化工厂和海洋采油平台钢结构上。

Experimental study on the durability of BFRP bars embedded in concrete

This paper presents an experimental study on the alkali-resistant properties of basalt fiber reinforced polymers （BFRP） bars under a typical concrete environment. BFRP bars were embedded in concrete and exposed to different aggressive environments, including tap water, saline solution and ambient temperature environments, to study the effects of the type of solution and relative humidity （RH） on the durability of BFRP. Meanwhile, BFRP bars were directly immersed in an alkaline solution for comparison. The acceleration factor describing the relationship between the alkaline solution immersion and the moisture-saturated concrete was also obtained. Aging was accelerated with a temperature of 60 ℃. The results show that the chloridion in the saline solution does not have any harmful effects on the degradation of the concrete-encased BFRP bars. Contact with an alkaline （high pH） concrete pore-water solution is the primary reason for the degradation of the BFRP bars. The degradation rate of concrete-encased BFRP bars is accelerated when a high temperature and a high humidity are present simultaneously. The degradation rate of the BFRP bars is relatively quick at the initial stage and slows down with exposure time. Results show that the degradation of 2.18 years in moisture-saturated concrete at 60 ℃corresponds to that of one year when directly immersed in an alkaline solution （other conditions remaining the same） for the BFRP bars analyzed.

环保型环氧改性聚酯浸渍漆在干式变压器上的应用研究

介绍了采用低毒活性稀释剂制备的环保型环氧改性聚酯浸渍漆,对比其与传统环氧改性聚酯浸渍漆的常规性能、贮存稳定性、环境耐久性等,并详细阐述了环保浸渍漆在干式变压器上的工程化应用。结果表明:环保型环氧改性聚酯浸渍漆的固化挥发份低,贮存稳定性、粘接强度及环境耐久性好,能满足干式变压器的应用要求。

Accelerating Effect of Wetting-Drying Cycles on Steel Bar Corrosion in Concrete

Raining and sun-shining processes in natural climate were simulated by water spraying and infrared lightshining alternately as wetting-drying cycles in accelerated durability test. The accelerating effects of the wet-ting-drying cycles and the variation of corrosion current density and corrosion potential of steel bar in concrete undersuch conditions were studied. The result shows that the main reason leading to accelerating corrosion of steel bar inconcrete is the wetting-drying cycles, which can cause the increase of corrosion potential difference between the an-ode and cathode of steel bar corrosion cell and the decrease of concrete resistance. Corrosion rate of the steel bar inconcrete under four typical conditions, including wetting-drying cycle, long time submerging in water, long time ex-posure to indoor and outdoor environment were measured and compared. The test results indicate that the corrosionrates under the four typical conditions are in the order of spraying and infrared light shining cycles, outdoor environ-ment, indoor environment, and submerging in water, respectively.

Durability related environmental zonation and design methodology for marine RC structures

A reliability-based quantitative durability design methodology is presented for reinforced concrete(RC)structures in the marine environment on the basis of natural exposure data derived from four berths(1.5,1.5,4 and 15 years)of a concrete port.More than 200 chloride profiles are obtained and analyzed.The relationship between nominal surface chloride ion concentration and altitude is discussed.Subsequently,the formula of the apparent chloride diffusion coefficient is proposed with consideration of the surrounding temperature,sodium chloride solution concentration,age factor and altitude.Then,the reliability-based method to predict the durability of RC structures is developed according to Fick s second law.Relationships between the predicted penetration depth of the chloride ion,the ratio of the wetting time per-period and the corresponding altitude are discussed.Subsequently,the environmental zonation methodology is established for concrete structures under a marine chloride environment by considering the ratio of the wetting time per-period of concrete as the zoning index.Finally,the corres-ponding durability design method for each zone level is established,which contains the durability design regulations of the specimen,and correction coefficients for different water/binder ratios,ages,temperatures and chloride ion concentrations.

Main properties of ultra-high performance fiber reinforced cement composites under couple effect of load and environment

This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.

Evaluation of long-term corrosion durability and self-healing ability of scratched coating systems on carbon steel in a marine environment

Defects in protective-coating systems on steel surfaces are inevitable in practical engineering applications. A composite coating system, including a primer, middle coat and topcoat, were used to protect carbon steel from corrosion in a marine environment. Two environmental additives, glass fibers and thiourea, were applied in the middle coat to modify the coating system. The long-term corrosion durability and self-healing ability of the scratched coating system were evaluated by multiple methods. Results of the electrochemical technologies indicated that the coating system that contained 0.5 wt.% fibers and 0.5 wt.% thiourea presented good corrosion protection and self-healing for carbon steel when immersed in 3.5% NaCl for 120 d. Evolution of localized corrosion factors with time, as obtained from the current distribution showed that fibers combined with thiourea could inhibit the occurrence of local corrosion in scratched coating systems and retarded the corrosion development significantly. Surface characterization suggested that adequate thiourea could be absorbed tmiformly on fibers for a long time to play an important role in protecting the carbon steel. Finally, schematic models were established to demonstrate the action of fibers and thiourea on the exposed surface of the carbon steel and the scratched coating system in the entire deterioration process.